314 ANN^UAL KEPORT SMITHSONIAN INSTITUTION, 1939 



the Louisiana and Texas deposits 95 percent of the world's supply of 

 sulfur came from Sicily. At present these two States supply the 

 greater part of the world's sulfur and more than 99 percent of the 

 domestic output. 



The United States possesses the only known natural gas fields in 

 the world that yield gas sufficiently rich in helium to warrant the ex- 

 traction of this element on a commercial scale. The richest helium- 

 bearing gases, those containing 1 to 8 percent, are found in southeast- 

 ern Kansas, southeastern Colorado, eastern Utah, and in the Texas 

 Panhandle. The production of helium on a large scale was bom of 

 the necessity to find during the World War a noninflammable substi- 

 tute for the extremely inflammable hydrogen gas in balloons and 

 dirigibles. The operation of experimental plants in Texas and Can- 

 ada, beginning in 1918, led to the erection in 1919 of a production 

 plant at Fort Worth, Tex., and later other plants, one by the Heliiun 

 Co. at Dexter, Kans., in 1927, and the other by the Bureau of 

 Mines near Amarillo, Tex., in 1928. 



American potash, like our helium, was first produced during the 

 World War and it now supplies a major portion of our domestic re- 

 quirements. An energetic search for possible sources of potash in 

 this country began in 1911. One of the possible sources thus investi- 

 gated was the Permian salt of Texas and New Mexico. Information 

 about the extent and character of the potash deposits in these States 

 acquired from oil company wells and from Government and private 

 core tests revealed commercial deposits of potash in New Mexico. 

 Shipments began in 1931 and they totaled 700,000 tons of crude pot- 

 ash salts in 1937. 



PETROLEUM RESERVES OF UNITED STATES 



Our petroleum reserves, because of the nature of the occurrence of 

 petroleum, are imperfectly known. Petroleum is a liquid contained 

 in the rocks deep below the surface in many small widely scattered 

 areas. It is discovered by the driller who is aided in his search by 

 the accumulated knowledge about oil and its occurrence. 



A number of estimates of the total petroleum resources of the 

 United States were prepared between 1909 and 1921. During this pe- 

 riod, however, it became evident that the unproved reserves in un- 

 known fields awaiting future discovery could not be estimated with 

 any degree of accuracy whereas the quantity of oil in the proved re- 

 serves, recoverable by then current methods of production, could be 

 estimated with reasonable accuracy on the basis of the past produc- 

 tion experience of depleted fields. The first estimate in which the 

 proved reserves were separated from estimates of undiscovered fields 

 was made in 1921 by the Geological Survey with the cooperation of 

 the American Association of Petroleum Geologists. In this estimate 



